Is PR negative less responsive to Arimidex?

Hi JuniperCat:

I see that they are reporting ER and PR separately, and they note that it may differ from ER and PR status determined by other methodologies (at page 3):

http://breast-cancer.oncotypedx.com/en-US/Professi...

Be sure to add those questions to the list of things to discuss with your MO to ensure accurate and current advice.

Meanwhile, the NCCN guidelines for Breast Cancer (Version 1.2016) indicate:

"Patients with invasive breast cancers that are ER or PR positive should be considered for adjuvant endocrine therapy regardless of patient age, lymph node status, or whether adjuvant chemotherapy is to be administered."

Thus, ER-positive status alone can justify endocrine therapy.

In addition, to my knowledge, ER and PR status determinations have been historically made based on the immunohistochemical tests conducted during tissue pathology, and the studies that led to approval of Arimidex for "Adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer" would have used those traditional methodologies by which you were/are considered ER+PR+.

This 2012 paper is a little heavy going, but seems to suggest that immunohistochemical methods (traditional pathology) are more sensitive and preferred:

http://www.nature.com/modpathol/journal/v25/n6/ful...

"The additional reporting of qRT-PCR ER and PR results on oncotype report confuses clinicians and unnecessarily creates doubt about validated immunohistochemistry assays."

Again, please be sure to discuss all your questions and concerns about PR status with your MO.

BarredOwl

Hi JuniperCat:

Do go back and check that prior report to see if you now understand it to be indicating PR negative. You may still want to discuss with your MO whether there are any implications (or not) of that statusfor your various treatment decisions.

BarredOwl

Hi JuniperCat:

I agree with Ruthbru. I am striving to die of something else hopefully when much older.

As you can imagine, very long-term follow-up is challenging for conducting a clinical trial. Five-year survival rates are measurable within most study time-frames, which is why they are used, but 5-yrs is an arbitrary cut-off point for breast cancer. While there are some non-breast cancers which if you make it past 5 years, you are pretty unlikely to suffer a recurrence, breast cancer behaves a little differently and the risk of recurrence goes out farther (even 20+ years). Rather than use the word "cure" or "cancer free", which may overstate the case, many use the term "NED" (no evidence of disease).

RuthBru is that 70% a 70% reduction of baseline risk, such that that the actual benefit achieved may be lower? If so, that personal baseline risk and the magnitude of reduction would be a point for discussion with the radiation oncologist.

With tamoxifen, I know it can reduce risk about 45%. But if the baseline risk was say 10% in a particular case, the drug may achieve a 45% reduction, reducing risk by 4.5% down to 5.5 %.

BarredOwl

Thanks Ruth. Even if the 70% is a relative risk (a point to confirm with the radiation oncologist), it is indeed a big downward modulation of one's personal risk. And I agree that the current NCCN guidelines include radiation if lumpectomy is chosen for IDC, Stage I, negative nodes:

"Radiation therapy to whole breast with or without boost to tumor bed or consideration of partial breast irradiation (PBI) in selected patients. It is common for radiation therapy to follow chemotherapy when chemotherapy is indicated."

BarredOwl